Device for the prevention of shutdown corrosion attacks in steam spaces and condensate recipients of steam installations



M. STEIN 3,050,040 DEVICE FOR THE PREVENTION OF SHUTDOWN CORROSION Aug. 21, 1962 ATTACKS IN STEAM SPACES AND CONDENSATE RECIPIENTS OF STEAM INSTALLATIONS 3 Sheets-Sheet 1 Filed Feb. 5, 1959 INVENTOR.

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DEVICE FOR THE PREVENTION OF SHUTDOWN CORROSION ATTACKS IN STEAM SPACES AND CONDENSATE RECIPIENTS OF STEAM INSTALLATIQNS Filed Feb. 5, 1959 3 Sheets-Sheet 2 FIG. 4

INVENTOR.

United States Patent Ofifice 3,059,04il Patented Aug. 21, 1962 3,050,040 DEVICE FOR THE PREVENTION F SHUTDOWN CORROSION ATTACKS IN STEAM SPACES AND CONDENSATE RECIPIENTS 0F STEAM WSTAL- LATIONS Marcel Stein, 528 E. 89th St., New York, N.Y.

Filed Feb. 5, 1959, Ser. No. 791,357 Claims priority, application Austria Dec. 5, 1958 4 Claims. (Cl. 122-4) The condensates of steam cause corrosion-attacks in steam installations during standstills or shutdowns. In spite of the drainage of the condensates by means of steam traps, etc. well known in the art the remaining amount of the condensate and moisture still causes considerable damage due to shutdown-corrosion attacks on the walls, in the traps, appliances and other parts of the steam spaces. Similar damages arise in condensate recipients like condensate return lines, condensate tanks, condensers etc. during shutdowns.

Devices according to this invention prevent these drawbacks by drying the steam spaces and condensed water recipients automatically during standstills or shutdowns.

The essential feature of thi invention consists in connecting the steam space or condensate recipients to be dried with the space containing the desiccant automatically during shutdowns as soon as the temperature of the steam space drop below a predetermined temperature below 212 F. This temperature preferably is roomtemperature. This connection is also shut off automatically as soon as steam is turned on and thus the temperature in the steam space rises above the predetermined level mentioned above.

One advantageous embodiment of my invention consists in reactivating the desiccant during normal plant operation of the steam space whereby the desiccant is heated automatically by means of the working steam itself, directly or indirectly. For the duration of this reactivation-period the space containing the desiccant is automatically connected with the ambient air in order to discharge the moisture expelled out of the desiccant. The connection between the desiccator space containing the desiccant and the ambient air is interrupted automatically as soon as the steam supply is shut off in order to preserve the water-adsorbing or absorbing capacity of the reactivated desiccant.

The outer surface of the steam space to be dried is used as the heating surface for heating of the desiccant in an advantageous embodiment of my invention. In this case the desiccant is heated permanently during normal plant operation. By this feature water adsorption or absorption from the ambient air is prevented during norm-a1 plant operation. The steam space cools down when steam supply is shut off. At a temperature above the lower reactivation limit of the desiccant actually used the remote control valve in the junction line leading to the ambient air is closed automatically. The steam space to be dried and the space containing the desiccant become connected automatically by means of a second remote control valve as soon as the temperature of the steam space drops below a predetermined level below 212 F. Thus the steam space is dried by the reactivated desiccant. The rising temperature of the steam space causes the remote control valve inserted into the junction line between the steam space and desiccator space to close automatically when steam supply is again started. The remote control valve in the junction line leading to the ambient air is opened automatically when the temperature in steam space rises above the lower reactivation limit of the desiccant actually used. Thus the vapors expelled out of the desiccant are discharged into the ambient air.

The invention also comprises means for drying several steam spaces independent from each other by one common desiccator unit during standstills or shutdowns. In this case the reactivation of the desiccant is performed in dependence of its saturation by one of the automatic devices known in the art.

Automatic means are provided to close the steam space from the ambient air for the duration of the desiccation period or the shutdowns if steamtraps, airvents and other apertures are designed to remain open during shutdowns.

A further object of this invention is the prevention of shutdown corrosion attacks in condensed water recipients like condensers, condensate return lines, etc.

The device for the automatic drying of steam spaces and of condensed water recipients during shutdown will be described in detail by taking reference to the accompanying drawings which show, by way of example, several embodiments thereof.

In the drawings:

FIG. 1 ilustrates the section of a tubular steam space to be protected against shutdown corrosion attacks and the automatic device for performing the desiccation or drying during shutdowns;

FIG. 2 represents a plan view of the same steam space and of the same automatic device;

FIGS. 3 and 4 illustrate diagrammatical schemes of further embodiment of the invention;

FIGS. 5 and 6 show embodiments for the desiccation of condensate recipients during shutdowns; and

FIG. 7 illustrates a modification of the embodiment shown in FIG. 6.

In FIG. 1, 1 denotes a part of the steam space to be dried, 2 the container carrying the desiccant 3, 5 the cover fixed by means of bolts 6 to the container which is fixed to the outer wall of the steam space preferably by welding. Container 2 and cover 5 enclose the desiccator space 4. The container sometimes may be omitted and the desiccant may be placed directly onto the outer surface of the steam space. The steam space 1 and the desiccator space are connected by means of the junction line 7, 8 into which a remote control valve B is inserted. A further remote control valve A is installed on the extension 10 of junction lines 7, 8. The remote control valves A and B are actuated automatically by means of the sensing element 9, preferably of the thermostatic type. The snuflie valve C prevents vacuum in the desiccator space.

The temperature in steam space drops near to the lower reactivating level of the desiccant 3 when the supply of steam is shut off. Thus sensing element 9 causes the valve A to close automatically in order to preserve the desiccants water adsorbing or absorbing capacity during the cooling period. Most of the condensate is drained by means well known in the art. The sensing element 9 causes the remote control valve B to open as soon as the temperature in the steam space 1 drops below a predetermined level under 212 F. Valve A, however, remains closed. Thus steam space 1 and desiccator space 4 are connected and sealed. The desiccant 3 reactivated during normal plant operation adsorbs or absorbs the remainders of condensate and moisture out of the steam space 1 thus preventing shutdown corrosion attacks.

Temperature rises in steam space 1 when steam supply is started. Sensing element 9 causes valve B to close above the predetermined temperature level 'below 212 F. while valve A remains closed. Valve A is opened automatically as soon as the temperature in steam space 1 rises above the lower reactivation limit of the desiccant. The desiccant 3 is heated by means of the steam in steam space 1 through the wall of said steam space. Thus the desiccant saturated by the condensate adsorbed during the shutdown is reactivated. The water expelled out of the desiccant in form of vapors is discharged through valve A into the ambient air. The desiccant accordingly is reactivated during normal plant operation period.

A steam pipe is illustrated in FIGS. 1 and 2 as a part of the steam space to be dried, but the process and the device according to this invention may be adapted to any kind of steam spaces like steam engines, steam containers, radiators, heating installations, etc. and my claim is not limited to the drying of steam pipes only.

The adaptability of the device according to FIGS. 1 and 2 is limited since only a certain temperature range is allowed for the reactivation of any desiccant. It is understood that the embodiment specified above can only be adapted it the normal plant operation temperature of the steam is between these limits. If the normal operat ing temperature of the steam in the steam space to be dried is above the allowable reactivation temperature range of the desiccant, the embodiment according to FIG. 3 should be used. FIG. 3 also may be applied in any case when the normal operating temperature of the steam is above the lower reactivation limit of the desiccant.

In FIG. 3 the steam space to be dried is denoted by 1, the sensing element by 9, a junction line between steam space 1 and air heater 12 by 11, a spring loaded suction valve on the inlet of the fan 16 by 14, a junction line between space of desiccation 17 and steam space 1 by 19, a remote control valve inserted into line 19 by 20, a steam trap by 13 and a remote control switch for the motor of fan 16 by 9'.

Temperature drops in steam space 1 when steam supply is shut off. Sensing element 9 interrupts the electric circuit of the driving motor of fan 16 by means of remote control switch 9' when the temperature in the steam space 1 approaches the lower reactivation limit of the desiccant. Thus, the flow of heated air sucked in through suction valve 14 by fan 16 and heated by air heater 12 in order to reactivate the desiccant in the space of desiccation 17 is stopped :for the duration of the shutdown. Later, sensing element 9 opens remote control valve '20 thus connecting steam space 1 and space of desiccation 17 when the temperature in the steam space drops below a predetermined level under 212 F. In this way steam space 1 is dried by the desiccant in the desiccator 17 during shutdowns.

Temperature rises in steam space 1 when steam supply is started and sensing element 9, preferably of the thermostatic type, closes valve 20, interrupting the connection between spaces 1 and 17. A second impulse emitted by sensing element 9 closes the circuit of the motor of fan 16 by means of remote control switch 9 as soon as the temperature in steam space 1 rises above the lower reactivating temperature limit of the desiccant.

The vacuum in the inlet '15 causes suction valve 14 to open when fan 16 runs. The air sucked in is heated by airheater 12 to a temperature most suitable for the reactivation of the desiccant. The heated air flows through space of desiccation 17, heats the desiccant in it, adsorbs the moisture expelled out of it and is discharged through the valve 18 into the ambient air. Thus the desiccant is reactivated during normal plant operation in a certain time. The motor circuit of fan 16 may be interrupted by means of a time delay device or by other methods Well known in the art when the reactivation of the desiccant is completed. At the same time spring loaded valves 14 and 18 close automatically.

The layout according to FIG. 4, and a device 21 well known in the art is to be applied if a number of independent steam spaces 22, 22', 22" should be dried by one common dessicator unit. Devices 21 of this kind are described e.g. in the USA. Patents 2,411,039, 2,506,578, 2,511,666. The same kind of automatic reactivation device also may be applied for individual drying of one steam space and should be applied when desiccant is heated by electricity. This is the case e.g. if the normal operating temperature of the steam is below the lower reactivating limit of the desiccant.

In FIG. 4 each independent steam space 1, 22, 22 and 22" is connected with the desiccating unit 21 by means of its individual junction line 19, 23, 23 and 23" respectively. An individual remote control valve 20, 24, 24' and 24 is inserted into each of these junction lines. These remote control valves are controlled by their individual sensing elements 9, 25, 25' and 25" which preferably sense the temperatures of the respective steam spaces 1, 22, 22' and 22".

The manner of function of this embodiment is similar to that described on hand of FIGS. 1-3. Each of the steam spaces 1, 22, 22, 22 is connected automatically with the desiccator unit 21 by means of opening the respective remote control valve 20, 24, 24 or 24", as soon as the temperature drops below a level under 212 F. The respective sensing element causes the pertaining remote control valve to close in order to interrupt the connection between the steam space and the desiccator unit 21 when steam supply is started in the steam space. This connection remains interrupted during normal plant operation.

Remote control valves 28, 28, 28 and 30, 30, 30" actuated by means of sensing elements 25, 25', 25 respectively are provided behind steam traps 27, 27', 27 and air vents 29, 29, 29 respectively when they are of the type remaining open for the duration of shutdown. These remote control valves are closed automatically at the same time when remote control valves 24, 24' or 24" are opened, respectively, and they are opened when remote control valves 24, 24 or 24" are closed by means of sensing elements 25, 25' or 25", respectively. Thus the steam spaces 22, 22 and 22" are sealed for the duration of shutdowns.

In FIG. 5 the main manifold is denoted by 32, the main by 35, the valve of the main 35 by 33, the sensing element of the main 3'5 by 34, the space of desiccation by 36; 37, 38, 39, 40 and 41 are remote control valves actuated by sensing element 34, preferably of the thermostatic type; valve 41 is provided with a time delay device to close after return line 46, 47 is drained; 26, 26' and 26" are shut 01f valves of the mains 35 branches; the junction line between main 35 and space of desiccation 36 is denoted by 43 and the junction line between condensate return line 46, 47 and space of desiccation 36 is denoted by 44; 47 is a water seal in the condensate return line 46 and 61 is a steam trap of the main 35.

Steam space 35 cools down as soon as the steam supply is turned off by means of valve 33. Then sensing element 3'4 closes remote control valve 37 in order to preserve the water adsorbing or absorbing capacity of the reactivated desiccant. Sensing element 34 simultaneously causes valves 38 and 39 to open, valve 40 to close and temporarily opens valve 41 as soon as the temperature in steam space 35 drops below a predetermined level under 212 F. preferably around room temperature. Condensate return line 46, 47 is drained by opening valve 41 temporarily. Thus the whole piping system is connected with the space of desiccation 36 and remains sealed during shutdowns.

Valves 38 and 39 are closed and valve 40 is opened when steam supply is started by the opening valve 33, and raising the temperature in steam space 35 above a predetermined level under 212' F. Sensing element 34 opens remote control valve 37 when temperature in steam space rises above the lower reactivating limit of the desiccant; Thus, humidity expelled out of the desiccant is discharged into the ambient air during shutdowns.

FIG. 6 represents another embodiment for drying condensate recipients like condensers, condensed water tanks, condensate return lines, etc. Besides the denotations already mentioned, 48 denotes a sensing element, 49 a small water seal, 50 an automatically controlled fan, 51 a desiccator unit automatically reactivating the desiccant, known well in the art per se which is connected with the condensate return line by means of its blow 01f line 58. A remote control valve 59 is inserted into the blow off line 58. Number 60 denotes a snuffle valve near the most remote end of the condensate return line 46; 61 is the steam trap adapted to drain the line 35, and 62 is an electric time switch to close or interrupt the circuit of the fan motor 50 automatically.

Sensing element 48 opens remote control valve 59 and closes simultaneously the circuit of fan motor 50 by means of remote control switch 62. Thus, dried air is blown under pressure through line 58 into the condensate return line 46, 47. This pressure discharges the condensate through the small water seal 4 into the condensate storage tank 45. After complete drainage the air current dries the traces of water and the moisture in the return line 46, 47. The time switch 62 opens the circuit of the fan motor 50 after a time determined by experience necessary for the drying of the condensate return line 46, 47. Switch 62 may be actuated by an air humidity differential sensing device 63 instead of a time delay device. As soon as the pipe network is fully dried, the humidity of the blown off drying air shows no difference as compared with the humidity of the entering air. In this case, air humidity difi'erential sensing device opens remote control switch 62 and stops fan motor 50.

Both the main 35 and the condensate return line 46, 47 may be dried by one common desiccator unit if a junction line 58, as shown in FIG. 7, is used instead of junction line 58, and steam trap 61 is of the type which remains open during shutdowns.

Sensing element 48 closes remote control valve 59 and shuts oif the electric circuit of the fan motor 50 by means of switch 62 which is also a time delay switch, at the same time. Any known desiccator units reactivating the desiccant automatically in dependence of its saturation condition may be used in this arrangement. The small water seal 49 prevents vapors rising out of the tank 45 from penetrating into the piping 47, 46 when its drying is already completed and fan 50 is stopped. Any nonaggressive gas may be used for drying.

What I claim is:

1. An arrangement for protecting steam enclosures against corrosion attacks during shutdown comprising, in combination, enclosure means to which steam is adapted to be supplied; closed container means adapted to contain a desiccator; first passage means connecting said container means with said enclosure means; second passage means connecting said container means with the outer atmosphere; first valve means in said first passage means and movable between an open and a closed position ofr opening and closing said first passage means, respectively; second valve means in said second passage means and movable between an open and a closed position for opening and closing said first passage means, respectively; and temperature sensing means in said enclosure means and operatively connected to said valve means for opening said first valve means and closing said second valve means when no steam is supplied to said enclosure means and the temperature therein drops below a predetermined temperature so as to connect said enclosure means with said container means whereby moisture contained in said enclosure means is absorbed by the desiccator in said container means and for opening said second valve means and closing said first valve means when steam is supplied to said enclosure and the temperature therein raised beyond a predetermined temperature so as to prevent steam from entering into said container means and to provide communication of said container means with the outer atmosphere so that moisture absorbed by the desiccator during the shutdown period may be discharged to the atmosphere.

2. An arrangement for protecting steam enclosures against corrosion attacks during shutdown comprising, in combination, enclosure means to which steam is adapted to be supplied; closed container means adapted to contain a desiccator; first passage means connecting said container means with said enclosure means; second passage means connecting said container means with the outer atmosphere; first valve means in said first passage means and movable between an open and a closed position for opening and closing said first passage means, respectively; second valve means in said second passage means and movable between an open and a closed position for opening and closing said passage means, respectively; temperature sensing means in said enclosure means and operatively connected to said valve means for opening said first valve means and closing said second valve means when no steam is supplied to said enclosure means and the temperature therein drops below a predetermined temperature so as to connect said enclosure means with said container means whereby moisture contained in said enclosure means is absorbed by the desiccator in said container means and for opening said second valve means and closing said first valve means when steam is supplied to said enclosure and the temperature therein raised beyond a predetermined temperature so as to prevent steam from entering into said container means and to provide communication of said container means with the outer atmosphere so that moisture absorbed by the desiccator during the shutdown period may be discharged to the atmosphere; and heating means operatively connected to said container means for heating the desiccator therein at least during the time said first valve means is closed and said second valve means is open.

3. An arrangement for protecting steam enclosures against corrosion attacks during shutdown comprising, in combination, enclosure means to which steam is adapted to be supplied; closed container means adapted to contain a desiccator, said container means being separated from but arranged in heat exchanging contact with said enclosure means so that the desiccator in said container means is heated when steam is supplied to said enclosure means; first passage means connecting said container means with said enclosure means; second passage means connecting said container means with the outer atmosphere; first valve means in said first passage means and movable between an open and a closed position for opening and closing said first passage means, respectively; second valve means in said second passage means and movable between an open and a closed position for opening and closing said second passage means, respectively; and temperature sensing means in said enclosure means and operatively connected to said valve means for opening said first valve means and closing said second valve means when no steam is supplied to said enclosure means and the temperature therein drops below a predetermined temperature so as to connect said enclosure means with said container means whereby moisture contained in said enclosure means is absorbed by the desiccator in said container means and for opening said second Valve means and closing said first valve means when steam is supplied to said enclosure and the temperature therein raised beyond a predetermined temperature so as to prevent steam from entering into said container means and to provide communication of said container means with the outer atmosphere so that moisture absorbed by the desiccator during the shutdown period may be discharged to the atmosphere.

4. An arrangement for protecting steam enclosures against corrosion attacks during shutdown comprising, in combination, enclosure means to which steam is adapted to be supplied; closed container means adapted to contain a desiccator; first passage means connecting said container means with said enclosure means; second passage means connecting said container means with the outer atmosphere, said second passage means having an inlet portion for leading air into said container means and an outlet portion for leading air out of said container means, said portions having each a free end opening into the atmosphere and an end opposite said free end and communicating with said container means; air heater means in said inlet portion for heating air passing therethrough; blower means in one of said passage means portions for causing,

when actuated air to flow from said free end .of said inlet portion through said heater means into said container means and through said outlet portion out of said container means; first valve means in said first passage means and movable between an open and a closed position for opening and closing said first passage means, respectively; second valve means in said inlet and outlet portions of said second passage means and movable between an open and a closed position for opening and closing said second passage means respectively and said valve means being moved to said open position when said blower means is actuated; and temperature sensing means in said enclosure means and operatively connected to said first valve means and said blower means for opening said first valve means while leaving said blower means deactuated when no steam is supplied to said enclosure means and the temperature therein drops below a predetermined temperature so as to connect said enclosure means with said container means whereby moisture contained in said enclosure means is absorbed by the desiccator in said container means and for closing said first valve means and actuating said blower means when steam is supplied to said enclosure and the temperature therein raised beyond a predetermined temperature so as to prevent steam from entering into said container means and to blow air heated by said air heater means over the desiccator contained in the container means so that moisture absorbed by the desiccator during the shutdown period may be discharged to the atmosphere.

References Cited in the file of this patent UNITED STATES PATENTS 1,687,458 Lancelot et al. Oct. 9, 1928 1,943,613 Lewis Ian. 16, 1934 2,328,521 Wittman Aug. 31, 1943 2,609,060 Kean-by Sept. 2, 1952 

